A lattice ciphertext policy attribute based encryption (CP-ABE) scheme is presented, in which the ciphertext policy achieved is the AND-gates on multi-valued attributes. The previous construction with AND-gates on multi-valued attributes as ciphertext policy is based on bilinear paring technology. In this paper, inspired by the recent progress of lattice identity based encryption scheme, we achieve this access structure from lattice technology. There are two constructions given, and both of them can be viewed as an extension and generalization of the lattice identity based encryption schemes proposed by Agrawal et al., respectively. In addition, our constructions are shown to be secure under the learning with errors assumption in the standard model.
A lattice ciphertext policy attribute based encryption (CP-ABE) scheme is presented, in which the ciphertext policy achieved is the AND-gates on multi-valued attributes. The previous construction with AND-gates on multi-valued attributes as ciphertext policy is based on bilinear paring technology. In this paper, inspired by the recent progress of lattice identity based encryption scheme, we achieve this access structure from lattice technology. There are two constructions given, and both of them can be viewed as an extension and generalization of the lattice identity based encryption schemes proposed by Agrawal et al., respectively. In addition, our constructions are shown to be secure under the learning with errors assumption in the standard model.
Ciphertext policy attribute-based encryption (CP-ABE) is a promising cryptographic technology that provides fine-grained access control as well as data confidentiality. It enables one sender to encrypt the data for more receivers, and to specify a policy on who can decrypt the ciphertext using his/her attributes alone. However, most existing ABE schemes are constructed on bilinear maps and they cannot resist quantum attacks. In this paper, we propose a multi-authority CP-ABE (MA-CPABE) scheme on ideal lattices which is still secure in post-quantum era. On one hand, multiple attribute authorities are required when user's attributes cannot be managed by a central authority. On the other hand, compared with generic lattice, the ideal lattice has extra algebraic structure and can be used to construct more efficient cryptographic applications. By adding some virtual attributes for each authority, our scheme can support flexible threshold access policy. Security analysis shows that the proposed scheme is secure against chosen plaintext attack (CPA) in the standard model under the ring learning with errors (R-LWE) assumption.
The recent promising results on the hardness of lattice problems have inspired the construction of several Attribute-based Encryption (ABE) schemes from the quantum resistant perspective. However, these schemes are insufficient enough for supporting real-world applications due to inherent quadratic overhead problem in the use of Learning With Error (LWE). To solve this problem, this paper proposed a Ciphertext-Policy Attribute-Based Encryption (CP-ABE) scheme from a more lightweight ideal lattice classes- Ring-Learning with Errors (Ring-LWE), that further called as CP-ABER-LWEscheme. Compared to existing R-LWE based ABE scheme, the proposed CP-ABER-LWEis capable to handle a monotone access structure and enjoys collusion resistance properties. We exploited Linear Secret Scheme (LSSS) to express a monotone access structure. For resist to collusion attack, we applied the private key randomization technique to blind the user's private key. The proposed scheme CP-ABER-LWEis further proven to be secure under the Decision Ring-LWEd,q,χproblem in the selective set model.
In Ciphertext Policy Attribute-Based Encryption (CP-ABE) system, a set of attributes is associated with the private keys of each user. Also, the ciphertext is attached with a policy which is defined over that set of attributes. A user can decrypt the ciphertext if the ciphertext’s policy is satisfied by the attributes associated hith her private key. Traditional CP-ABE schemes, based on number theoretic problems, rely on a trustworthy central authority. But in many distributed applications it is expected that such authorities should be decentralized to avoid the risks of single-point failure. While the number theory-based hardness problems are prone to quantum attacks, lattice-based hardness problems can resist such attacks. In this paper, we construct a Decentralized Ciphertext-Policy Attribute-Based Encryption (DCP-ABE) scheme. Under this scheme, any participating entity can act as an authority by creating a public key. The athority utilizes the users’ attributes to generate the private keys for them. Any user can encrypt data in terms of any monotone access structure over attributes issued from any chosen set of authorities. Hence the protocol does not depend on any central authority. We utilize Learning With Errors over Rings (R-LWE) as the underlying hardness assumption for te protocol. The proposed post-quantum protocol achieves security under selective-set model whereby adversaries are allowed to corrupt any authority only statically through adaptive key queries.
Broadcast encryption remains one of the few remaining central cryptographic primitives that are not yet known to be achievable under a standard cryptographic assumption (excluding obfuscation-based constructions, see below). Furthermore, prior to this work, there were no known direct candidates for post-quantum-secure broadcast encryption. We propose a candidate ciphertext-policy attribute-based encryption (CP-ABE) scheme for circuits, where the ciphertext size depends only on the depth of the policy circuit (and not its size). This, in particular, gives us a Broadcast Encryption (BE) scheme where the size of the keys and ciphertexts have a poly-logarithmic dependence on the number of users. This goal was previously only known to be achievable assuming ideal multilinear maps (Boneh, Waters and Zhandry, Crypto 2014) or indistinguishability obfuscation (Boneh and Zhandry, Crypto 2014) and in a concurrent work from generic bilinear groups and the learning with errors (LWE) assumption (Agrawal and Yamada, Eurocrypt 2020). Our construction relies on techniques from lattice-based (and in particular LWE-based) cryptography. We analyze some attempts at cryptanalysis, but we are unable to provide a security proof.
In recent years, the research on ciphertext-policy attribute-based encryption (CP-ABE) scheme design based on learning with errors (LWE) has been a challenging problem, and many researchers have made a lot of attempts at it. At EUROCRYPT 2021, Datta, Komargodski, and Waters proposed the first provably secure direct CP-ABE construction that supports NC1 circuit access structures. Improving on their work, we propose a CP-ABE scheme. Technically, we use the new lattice two-stage sampling technique of Lai, Liu, and Wang (EUROCRYPT 2021) in the key generation phase instead of the extended trapdoor sampling technique. In this way, we obtain a CP-ABE scheme, which is at least as secure as the original scheme under the same conditions, and has a shorter ciphertext; we provide an innovative design idea for designing CP-ABE schemes only based on LWE, although this is only a partial theoretical work.
Ciphertext-policy attribute-based encryption (CP-ABE) serves as a fundamental cryptographic primitive for fine-grained data access control. However, existing schemes, primarily based on bilinear maps or lattice hardness assumptions, generally suffer from large system parameters, key sizes, and ciphertext sizes, which severely restrict their deployment in resource-constrained scenarios. To address this challenge, a novel CP-ABE scheme based on supersingular elliptic curve isogeny (SI-CP-ABE) is proposed. This scheme integrates the action of isogeny ideal class group with linear secret sharing schemes, achieving efficient fine-grained access control in a post-quantum security setting. Regarding security, two new hardness assumptions—P+-CSSCDH and P+-CSSDDH—are proposed, based on which the scheme is rigorously proven to satisfy indistinguishability under chosen plaintext attack in the selective security model. To further enhance performance, an optimized scheme is designed based on SI-CP-ABE. Furthermore, based on the core algebraic structure of SI-CP-ABE, a post-quantum Naor-Reingold-type pseudo-random function with authentication capability is constructed, thereby enriching the building blocks for post-quantum cryptographic protocols.